Mixing machine



Jan. 12, 1937. D. Mel(` HEPBURN I 2,067,236

MIXING MACHINE Filed Jan. 22, 1934 2 Sheets-Sheet l Jan. 12,1937. D, MSK, HEPEgURN y2,067,236

MIXING MACHINE Filed Jan. 22, 1954 2 Sheets-sheet 2 Patented Jan. 12, 1937 UNITED STATES PATENT OFFICE NIXING MACHINE Application January 22, 1934, Serial No. 707,730

8 Claims.

This invention relates to a road surfacing mixing machine and to the manufacture of surfacing materials therein, the said materials being of such character that they can be mixed on the road surfaces or where the aggregate originates, whether they be a bituminous or Portland cement mixture. But this invention is principally designed so that the material can be cheaply mixed on the road surfaces and can be deposited there- 10 on Without any further preparation.

The principal object of my invention is to eliminate the uncertainty of the haphazard methods by which mixes are made on the road surfaces today; for example:

After the stone, which is to be treated, has been spread and leveled on the road surface, and the bituminous materials have been applied to the stone, the mixture is then bladed from one side of the road to the other and sloshed around in what appears to the average engineer to be a rather careless manner and contrary to What would be called go'od practice, until all surfaces of the stones are thoroughly coated. In the present stage of this type of mixing, practically all types of farm implements are used to stir or agitate the mixture, such as drag and spike-tooth disc harrows, orchard cultivators, drawn by power driven graders, or any other tool or instrument which may be available for the purpose. The coated stone is then spread, by the use of a blade grader,

then the mixture is rolled, chinked and penetrated with bitumen again, and surface treated, when another application of the roller is used. The road is then open to trailic. Such types of V road are known to the trade to-day as retread, road mix, or mixed-in-place or bituminous surface course macadam. Even with these methods of uncertainty in mix, these types of roads have been fairly successful, and several States in the East have laid a large milage of these roads.

The principal object of my invention is to eliminate the uncertainty in the mix incident to the above methods, and to produce a material,

mixed on the road, all of which is passed through a mechanical mixer, very similar to the type of mixer used for years for mixing paving materials in stationary plants, and in this Way eliminate the uncertainty of mix and produce a mixture Where every stone is coated With the proper amount of bitumen.

Another important object of my invention is the production of a material that will contain the same proportions and quantities of ingredients, as compositions mixed in a stationary plant contain. In a machine-mixed material, no excess bitumen is present, because the material is agitated sufficiently to coat the entire aggregate without excess quantities of bitumen, for a machine eiects a most thorough agitation and 5 a consequent distribution of the bitumen over the surfaces of the aggregate such as can not be effected by grading and blading and scraping inert material lying on the road surface. It is a known fact to the art that the bitumen content 10v has to be increased, when thorough mixing is eliminated, in order to coat the aggregate by sloshing the material instead of thoroughly kneading and working the particles together.

Another object of my invention is to produce a 15 road material scientifically controlled by a formula so that it is an equal to the plant premixed material, and, by my novel V method, the quantities of the ingredients can be controlled accurately although the mixing of the material 2O is continuous after the mixing operation is started on the road.

In order to control the quantities in the mix that is hatched on the road surface, I use the novel method of spreading on the roadway suf- 25 cient stone per square yard for 2" or 21/4 compressed finished pavement, which is approximately pounds to the square yard, and in order that the road may be kept open to travel, I spread the stone required for the entire pave- 30 ment on half of the pavement width. I then deposit on this stone, the proper amount of liqueer (if I desire to use same) per square yard, and then follow this up by an application of bituminous material to the top of the stone, the 35 amount varying with the different types or formulae that I may use. I then drive the forward edge of a scoop or pan under the entire mass sloWly and progressively so that the mass slides upwardly on the scoop into the mixers, 40 which blades and stirs the material until every particle of the aggregate is thoroughly coated with the bitumen. During this mixing operation, the other ingredients, that I may desire in the mix, are added, they being of a small relative 45 amount per ton of mix. As this material is delivered from the mixer, it is deposited again on the road behind the mixer and is ready to be leveled or bladed to a thickness of about 3 inches at the points of minimum depths and when rolled, 50 this will produce a finished depth of approximately 2%, inches. Thinner pavements have not been found satisfactory, or thinner re-surfacings than 2% inches, where the material has been bladed by the mixed-in-place methods used to- 55 day. There are several reasons for this. The excess bitumen that has to be used, due to the poor mixing obtained by the present methods, and the quantity of cut-back used in the bitumen, makes the material such that a surface treating is necessary to properly seal the road and bind it, and if a pavement is laid thinner than 21/4 inches, the excess bitumen makes it impractical and produc-es a material too rich in bitum-en, but by my machine-mixed material, the material produced is of a character exactly the same as pre-mixed plant material, and any desired thickness can be laid on the road surface, or any number of surfaces can be laid on the same road. If a two course mix is desired, the road can. be. treated twice by using a relatively coarse stone in the base, and after it is rolled into place and compressed, a relatively thin course or wearing surface can be placed over the base course. Y,

Another object of my invention is the elimination of elevators havin-g moving parts for elevating the stone and bitumen mixture to any substantial height in order to deposit it into the mixer proper. No mechanical means, other than the scraper blades, dividing the material and guiding it into` the mixing troughs, are necessary, as the revolving mixing paddles take it away and convey it through the mixing troughs or chambers as fast as the scraper blades deposit it at the opening in the trough and the slow movement of the mixer over the roadway guides the measured or loatched` materials into the mixing trough, where it is immediately picked up and agitated by the paddles in the mixer and where the remainder of the ingredients desired in the mix can be added, and the mixed material is deposited from the other end of the mixer thoroughly coated and ready for spreading followed by immediate rollin-g.

Another object of myinvention is the novel method by which the material is ploughed or bladed and guided into the mixer chamber proper, without the use of any elevators or conveyors. The material is scooped into the mixer by the scoop being continually 'slowly forced forwardly under the material, and without the use of any conveying equipment having moving parts, such as elevators or conveyors, by simply towing or transporting the machine on the roadway, which largely increases the capacity of the machinery and makes the operation practical, as the handling, in a moving conveyer, of bitumen and stone, in a sticky mass, is a difficult operation, because the bitumen clogs the elevator or conveyor to such an extent that the operation is very difficult, if not impractical. My method described herein, eliminates the necessity of such equipment and also cheapens the operation.

Other objects of my invention will appear in the specification and claims below.

Referring now to the drawings forming a part of this specification and in which the same reference characters are used throughout the various views to designate the same parts,

Fig. 1 is a plan View of an'apparatus embodying my invention.

Fig. 2 is a side elevational View of the same.

Fig. 3 is a transverse vertical sectional View on the line 3 3 of Fig. 2.

Fig. 4 is a fragmentary vertical cross-sectional view showing a scoop rigidly secured to the front of the mixer and provided at its Aforward edge with hinge plates or scraper blades.

Fig. 5 is a view similar to Fig. 4 but of a modied construction wherein the scoop is hingedly secured to the front of the mixer.

In the drawings, A denotes the paddles which are used in mixing the material by revolving them in the mixing chamber or chambers D-D and are so designed that the paddles A consecutively carry the material in a single direction and automatically discharge the mixed material at the rear of the mixer. l

The wheels B are adjustable so that they keep the frame of the machine elevated to a height suincient to put the load on the wheels and to keep the front end of the scoop E bearing slightly on the scraper blades F.

In Fig. 2 is shown the adjustable screw shaft C for raising or lowering the bearings supporting the Wheels B.

The mixing chambers D-D are supported from the frame G of the machine so that the bottoms of the mixers D-D slightly clear the roadway over which the machine is moved. This frame G is kept as near aspossible to the roadway to cut down the height requiredv to lift the material from the roadway into the mixing charnbers D. Y Y Y The scoop or pan E isp-lowed or pushed into and under the batched material on the roadway and has a division e with short relatively sharp vertical forward edge in the middle so that 'onehalf of the material is guided into each mixing chamber D. The hinged scraper blades F which are Vfastened to the front end of the scoop or pan E with hinges K are'positioned with respect thereto that two-thirds of the plates F extend forwardly beyond the front edge of the scoop E. The purpose of these scraper blades F is to keep the machine from digging in and the plates F are preferably about 12 inches in width so that they will individually follow the contour of the roadway immediately preceding the scraper blades. They are hinged and so mounted as to have a movement of an inch or more at their front edge. Theycan accommodate themselves to any unevenness on the roadway. The frame G supports the entire machine.

A gasoline engine I-I or any other suitable type of power, and having a power shaft h, is mounted upon the frame G for revolving the main shafts I-I which support the paddles A ofthe mixers D as indicated in the drawings by the sprocket wheels L and the sprocket chains M.

The hopper J mounted upon the mixer frame is for containing ingredients other than regular aggregate and bitumen fromwhich small quantities may be discharged from time totime by opening the .gates 7'-y'. These ingredients may be lime, with or without fines or dust of mineral matter. l

In Fig. 5 the scoop E is movably mounted with respect to the mixing chambers D on hinges K so that the plates F may more freely follow the unevenness of the ground over which they slide as they are pushed into the course of paving material lying thereon and composed, in the main, of aggregate and bitumen and a liqueer, that is to say, a solvent for the bitumen, which increases its fluidity sufficiently to be spread evenly over the surface of the aggregate when submitted to a thorough agitation, such as is provided in the mixing chambers D.

An important feature is the automatic contour plates or scraper blades F, which are hinged to the edge of the scoop or pan E one-third of their length from theend'funder the pan E. Approximately two-thirds of the plates always follow the road surface by gravity, as the hinge K is hinged to the rear of the middle of the plates and because the hinges are loose and friction will not interfere with their action. These plates are a big factor in scooping the entire mass from an uneven surface of the road that is being treated.

The mixers D are so attached to the machine that they clear the road surface by only about three or four inches. By keepin-g the mixers this close to the road surface, I reduce considerably the problem of elevating the bitumen and stone mixture from the road surface into the mixing chambers D. The scoop E on the front of the mixer D, is supported at its front point of contact on a number of flat plates F that are each separate and can be elevated or inclined independently-allowing each plate to follow the contour of the road surface directly under each independent plate. For instance, if the road should have a slight depression at the middle of the surface over which the machine is being transported, and I had only a solid plate connected to the nose or front end of the scoop, the material deposited in the declined center section would be passed over and remain on the surface without passing through the mixer. But due to the hinged plates F which are fastened with a fulcrum or hingeV K, only one-third of the distance from the rear end of the plate and being relatively narrow in width, the weight of the plate plus th-e weight of the material that is deposited on its surface causes the plate to decline or follow into any depression and clean out the holes or depressions regardless of the height of the road surface at each side of the frame supporting the twin mixers.

I use no elevators other than a scoop E which is very similar to a dust pan with side walls e on each one to guide the materials into the mixer chamber or chambers proper. The resistance of the materials being deposited on the road surface causes the pans or scoops E to pass under the materials and push them up the slight elevation of the pan into the mixing chamber or chambers D, without the use of any elevators, conveying belts or propeller screws-thereby simplifying the machine and increasing the speed at which it can be operated. I have ample capacity to load the mixing chamber or chambers as fast as they can properly mix the materials.

In the mixing chamber proper, the paddles A are all of the shovel or turning-over design, so that they actually shovel the mass from one paddle to another and each operation is a thorough mixing operation each time a mixing paddle turns over the mass, and as the mixing chambers D are twenty feet long, there is a continuous mixing and turning of the mass, so that it is thoroughly mixed before it reaches the rear of the chamber, where it is automatically ejected from the machine.

Any type cf pavement can be manufactured in this machinesuch as Portland cement concrete roads, with a speed and low cost below any of the types of mixing machines known to the art to-day.

Another feature of this machine is that all of the ingredients can be properly batched in the exact quantities on the road surface, first making one big batch with the proper amount of stone, sand and Portland cement to the square yard of surface, as any height of materials desired on the surface of the road can be successfully handled by this machine. The same condition applies to a bituminous concrete, that may be desired as a wearing surface or a treatment of a sandy soil secondary road, where it is desired to treat with a bituminous binder for several inches of its surface can be successfully treated with this machine at a very low initial cost, and a wearing surface produced that will last for years.

Another advantage of this machine is that I am able to batch the materials in the exact proportions on the road surface, then scoop or plough or push them into the mixer where they are continuously mixed, and with a capacity greater than has been used for mixing road materials heretofore. Enough material can be mixed in a day to surface three or four miles of roadway, if it is desired.

In operating the mixing machine, the batched materials which have been placed double thickness on one half of the roadway are ploughed or scooped into the mixing chambers simply by the action of towing my machine along the highway, the weight and resistance of the bulk material deposited on the road surface to be mixed is ample to elevate the materials into the mixing chambers which are only elevated a few inches above the level of the roadway.

As soon as the materials are ploughe-d by the action of towing the machine to a depth of about twelve inches onto the pan or scoop E, the paddles A of the mixers revolving at this section of the pan or scoop, pick up the materials and start the mixing and intermingling of the batch and from this point until the batch is expelled at the other end of the mixer, the power operating the mixers conveys the material throughout the mixing operation.

The wheels B supporting the machine are adjustable by bearings attached to threaded shafts or supports C and can be adjusted, 'and the rear end of the mixing chambers can be elevated to any height desired. This control of elevation of the rear of the machine also adjusts the speed with which the batch is carried through the mixing chamber or chambers. If it is desired to lengthen the time of mixing the batch, the elevation of the rear will increase the time required for the material to pass through the mixing chamber or chambers.

Another advantage of this feature is in the mixing of a concrete road, by elevating the rear of the machine to six or eight inches. The material can be expelled to the thickness desired for the finished design and thickness for a foundation or roadway.

From the foregoing it must be apparent that the apparatus will operate very well on a batch of stone with the liqueer and the bitumen applied to the top of the layer when the layer or course is put or laid on a hard foundation or hard roadway on which the forward edges of plates F slide under the batch, and between the batch and the hard roadway. This hard foundation or roadway may have uneven spots in its surface. It may not be level, and it is likely to be crowned or it might be` depressed as by a hollow in the middle, but when the apparatus is drawn or propelled forwardly the forward edges of the Scrapers F will always slide over and on this hard support and into or over whatever of irregular hollows or eievations there may be in such surface. The batch to be treated in the machine is preferably supported on a be-d or roadway hard enough to prevent the forward edges of the blades F to dig into it as the scoop is pushed into and under the loose course of paving material thereon.

Having thus described my invention, what I claim and desire to protect by Letters Patent of the United States is:

1. A machine for scooping up, mixing and redepositing road surfacing materials previously batched as a layer on a hard roadway surface, comprising in combination a mixing chamber, a scoop in front of said mixing chamber arranged to plow into said mass or layer of material as the machine travels forwardly, the weight and resistance of such material being utilized to cause the same to slide rearwardly over the scoop and to be delivered to the mixing chamber without the aid of movable conveyers or baskets, and means within said chamber operative to thoroughly mix the material delivered thereinto; to slowly move the material rearwardly through said mixing chamber; and to discharge said materials therefrom to the roadway, and means at the forward edge of said scoop for following the contour of the road, said means including a plurality of scraping blades attached to the nose of the scoop for movement with respect to said nose and independent movement with respect to each other.

2. A machine for scooping up, mixing and redepositing road surfacing materials, comprising a mixture of materials such as mineral aggregate and bituminous cement which have been previously spread as a layer overa hard surfaced roadway, comprising in combination a supporting frame, a mixing unit mounted on said frame, a scoop arranged to slide under said surfacing materials and cause them to slide upwardly thereover for delivery to said mixing unit, said scoop being provided with a continuous series of selfadjusting blades freely pivotally secured to the forward edge of said scoop so that the forward edges of said blades automatically foilow the irregularities of .or in said hard surface of the roadway to clean and scrape up efficiently the materials that have been hatched as a layer on said road surface, and means to operate said mixing units as the said machine is advanced forwardly slowly to force said blades o-f said scoop to slide under said batched material and the material to slide upwardly over the upper surface of said scoop into said mixing chamber.

3. A machine for scooping up, mixing and for re-depositing a batch of road surfacing material previously placed on a hard roadway surface as a course or strata and consisting of materials such as a mineral aggregate and a bituminous cement, said machine comprising in combination a frame, mixing means mounted on said frame, the bottom of said mixing means being low and close to the surface of said roadway, a scoop in" iront of said mixing means adapted to be progressively slid under said course of batche'd imaterial and to deliver the said material into `said mixing means, and means at the forward edge of said scoop for continuously following the irregularities in the contour of the roadway surface on which said course of materiallies, said means including scraping blades mounted for pivotal movement with respect to the forward edge of said scoop.

4. A machine for scooping up, mixing and redepositing a mixture of materials such as mineral aggregate and cement previously batched and placed as a course on a hard roadway surface, comprising in combination a framework, a material mixing unit mounted in said framework and means for operating the same mounted on said" framework, and a scoop at the front end of said mixing unit, nose members for said scoop the forward edge portions of which lie lon and closely follow the irregularities in the contour of the surface of the said road surface and slide under said course of hatched material, said scoop and nose members being adapted to elevate the batched material from the road surface for discharge of the same into said mixing unit, said mixing unit being provided with a series of mixing blades, means to rotate said blades to distribute said cement evenly over the surface of each piece of aggregate, to cause said aggregate to slowly traverse said mixing unit during said stirring and to deliver said material out of the rear end of said mixing unit onto the roadway.

5. A machine for scooping up, mixing and redepositing road surfacing materials, comprising materials such as a mineral aggregate and a cement therefor placed as a layer or course on a hard surfaced roadway, comprising in combina-Y tion a portable frame, an elongated mixing chamber open at both ends mounted on said frame, a scoop at the front end of said mixing chamber and provided with lateral guiding surfaces between which the material is guided over the top of said scoop into the front end of said mixing chamber, said scoop being provided with blade members loosely pivoted to the front edge of said scoop and with their forward edges resting on said hard surface of said roadway torfollow the irregularities in the contour of said hard surfaced roadway and to travel, when said machine is advanced, between said road surface and said material hatched thereon.

6. A road mixing machine adapted to be transported along a roadway for scooping up, mixing and then re-depositing a mixtureof materials such as mineral aggregate and a cement therefor previously batched ona hard roadway surface, said machine comprising a portable frame, a material mixing unit mounted thereon and slightly elevated above the plane of said roadway and open at the front and rear ends thereof, a scoop in front of said mixing unit, making a small angle with the plane of said roadway and affording a smooth upper surface over which said road surfacing materials, scraped from said roadway by saidscoop, slide upwardly into the forward end of said mixing unit, the forward edge of said scoop being provided with a series of scraper blades, loosely pivoted to the forward edge of said scoop to closely follow the contour of the roadway as they are forced under the hatched material on said roadway to provide for an enicient removal of substantially all of said material from said roadway into the scoop, and mixing blades in said mixing unit operative to thoroughly mix the materials delivered thereto, to move said materials rearwardly to and through said mixing units and to discharge said material .to the roadway through the open rear end of said unit.

7. In a mixing apparatus for mixing road materials, comprising materials such as a mineral aggregate and a cement therefor placed as a course on a roadway in proper portions, comprising in combination a transportable frame, a mixing unit mounted thereon low to substantially just clear the surface of the roadway, a pan or scoop loosely pivoted at its rear end to the for-v ward end of said mixing unit and making a relatively small angle with the road surface, the forward edge of said scoop being provided with a series of blades loosely pivoted to the forward end of said scoop and lying flat on the surface of the road and adjusting themselves automatically to follow the irregularities in the road surface so that when said machine is advanced over said roadway, said blades slide under the course of said materials on said roadway, forcing them to slide upwardly over said blades and said scoop for delivery to said mixing units.

8, A mixing and delivering machine which can be transported over a roadway to automatically pick up materials from the roadway, deliver them to a mixer and then expel them behind the machine on the roadway in a thoroughly mixed condition characterized by the combination of a frame, a mixer mounted low on said frame to blades loosely pivoted to the forward edge of said 5 scoop at points between the front and rear edges of said blades to lie flat on the surface of said roadway and to slide thereon under said material when said machine is advanced to force said material upwardly over said blades and said 10 scoop into the said mixer by the resistance and the weight of the course of materials on the roadway.

DONALD MCKNIGHT HEPBURN. 

